Evaluation of sunscreen protection by measurement of epidermal DNA synthesis.

Different sunscreens were tested to determine their protection of epidermis from ultraviolet light effects. Ultraviolet light-induced changes in hairless mouse epidermal DNA synthesis were used for measurement of sunscreen protection. Visual assessment of erythema and edema was also performed. This initial study has evaluated sunscreens containing para-aminobenzoic acid (PABA) as the principle sunscreen chemical. These experiments were conducted using fluorescent sunlamp tubes and hydroxylapatite extraction of epidermal DNA. The ultraviolet light exposure was measured using a recording radiometer. The results showed that the sunscreens tested were able to partially prevent ultraviolet light induced changes in epidermal DNA synthesis. It may be possible to use this assay as one of the initial evaluations of potential ultraviolet light protectants.